PaymentApp: Implement respondWith() in PaymentRequestEvent. (content side)

components/payments/content/payment_app.mojom

Index: components/payments/content/payment_app.mojom
diff --git a/components/payments/content/payment_app.mojom b/components/payments/content/payment_app.mojom
index 0d9f7c655ad95ce00108c6592d6e4bf1858121e4..d0bb06cd3d8eaea278057140f6759eef489065ce 100644
--- a/components/payments/content/payment_app.mojom
+++ b/components/payments/content/payment_app.mojom
@@ -42,3 +42,8 @@ struct PaymentAppRequest {
   array<PaymentDetailsModifier> modifiers;
   string optionId;
 };
+
+struct PaymentAppResponse {
+  string method_name;

[Tom Sepez, 2017/03/07 17:22:39]

What are the restrictions on the values of these two fields?
These are only processed in a renderer?

[zino, 2017/03/27 15:27:04]

As I know, there are no restrictions in spec side.
The spec says that "Payment method security is outside the scope of this
specification and is addressed by payment handlers that support those payment
methods.".

The spec concept is providing a web based payment app using JS with service
worker.
So, we can not sure that the payment app provider what they want. So, it is
difficult to restrict the values of the method and details explicitly.

I think we can add length limits for them. Do we need them in mojo?

+  string stringified_details;
+};